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Activity 002: Multi-Material Blasting Technique Lab

Activity ID: U10M2-ACT-002 Duration: 45 minutes Objective: Practice blasting technique on three different substrate materials, adjusting parameters for each to achieve specified surface finishes.

Overview

Students apply the material-specific techniques covered in the slides by blasting mild steel, aluminum, and wood samples. Each substrate requires different pressure, angle, and speed settings. Students learn to adjust on the fly and evaluate their results.

Materials & Equipment Needed

  • Blast cabinet, configured with glass bead media 100–170 mesh
  • 1 mild steel coupon (3" x 5" x 1/8")
  • 1 aluminum plate (3" x 5" x 1/8", 6061-T6)
  • 1 wood sample (3" x 5" x 1/2", pine or poplar)
  • Masking tape for creating pattern boundaries
  • Pressure regulator (accessible during operation)
  • Surface roughness comparator (optional)
  • Magnifying loupe (10x)
  • PPE: safety glasses, N95 respirator, hearing protection
  • Student technique log worksheet

Instructions & Procedure

Phase 1: Setup and Baseline (10 minutes)

  1. Verify cabinet is loaded with glass bead media 100–170 mesh
  2. Perform pre-operation inspection (reference Activity 001 checklist)
  3. Set initial pressure to 60 PSI
  4. Apply masking tape to create three 1" zones on each sample:
  5. Zone A: 45° angle
  6. Zone B: 90° angle
  7. Zone C: Your choice (experiment)
  8. Label each zone with permanent marker on the masking tape

Phase 2: Steel Blasting (10 minutes)

  1. Set pressure to 60 PSI
  2. Blast Zone A at 45°, 6" standoff, 2"/sec travel speed — 3 passes
  3. Blast Zone B at 90°, 6" standoff, 2"/sec — 3 passes
  4. Blast Zone C at your chosen angle and speed — 3 passes
  5. Remove sample, remove tape, examine results with loupe
  6. Record observations: Which zone has deepest profile? Smoothest finish? Most uniform?

Phase 3: Aluminum Blasting (10 minutes)

  1. Reduce pressure to 35 PSI — critical for soft aluminum
  2. Blast Zone A at 45°, 8" standoff, 3"/sec — 3 passes
  3. Blast Zone B at 90°, 8" standoff, 3"/sec — 3 passes
  4. Blast Zone C at your chosen parameters — 3 passes
  5. Remove, examine, and record. Note any differences from steel results.
  6. Check for media embedment — glass bead is safer than aluminum oxide for this substrate

Phase 4: Wood Blasting (10 minutes)

  1. Reduce pressure to 20 PSI — wood is very soft
  2. Blast Zone A at 45° with the grain, 12" standoff, 3"/sec — 2 passes
  3. Blast Zone B at 90°, 12" standoff, 3"/sec — 2 passes
  4. Blast Zone C at your chosen parameters — 2 passes
  5. Remove, examine. Note grain raised vs. compressed texture.
  6. Document how the wood responded differently than metals

Phase 5: Analysis and Comparison (5 minutes)

  1. Arrange all three samples side by side
  2. Compare Zone A results across all three materials
  3. Write a brief analysis: What did you learn about adjusting technique for different materials?

Discussion Points

  • Why did the aluminum require lower pressure than steel?
  • How did the wood respond to 90° vs. 45° blasting?
  • What would happen if you used 60 PSI on the wood sample?
  • How would results differ with aluminum oxide media instead of glass bead?

Expected Outcomes

  • Steel shows clear profile difference between 45° (matte cut) and 90° (peened satin)
  • Aluminum shows subtle but detectable texture change at lower pressure
  • Wood shows dramatic grain raising at 90°, smoother texture with grain at 45°
  • Students demonstrate ability to adjust all five technique variables

Assessment Rubric

Criterion Excellent (4) Proficient (3) Developing (2) Beginning (1)
Pressure adjustment Correct pressure for each material Minor deviation Same pressure for all Excessive pressure used
Technique consistency Uniform coverage all zones Minor inconsistencies Uneven coverage Poor technique control
Analysis depth Detailed comparison with reasoning Good observations Basic observations only Minimal analysis
Safety compliance Full PPE, all procedures followed Minor omission Some procedures skipped Safety issues

Safety Considerations

  • Reduce pressure before switching to softer substrates — over-blasting damages material
  • Wood dust is combustible — ensure dust collector is running and no ignition sources nearby
  • Aluminum dust is also combustible in sufficient concentration — normal cabinet operations are safe but never accumulate large quantities
  • Clean cabinet between material changes if strict cross-contamination prevention is required
  • Wash hands after handling blasted samples

Last Updated: 2026-03-19